Alexandria Ocasio-Cortez said the U.S. is running concentration camps. Historians are divided on her statement.

Recent assertions by Rep. Alexandria Ocasio-Cortez, D-N.Y., that U.S.-run detention centers for migrants are "concentration camps" drew immediate rebukes from some politicians, Jewish groups and social media users.

"This administration has established concentration camps on the southern border of the United States for immigrants, where they are being brutalized with dehumanizing conditions and dying.

This is not hyperbole. It is the conclusion of expert analysis," she tweeted June 18.

Her tweet didn’t specifically mention Nazi Germany, but she used the term "never again" on her Instagram, a phrase often used as a warning to prevent another genocide like the Holocaust.

In a subsequent tweet, Ocasio-Cortez offered a distinction between "concentration camps" and "death camps."

"And for the shrieking Republicans who don’t know the difference: concentration camps are not the same as death camps. Concentration camps are considered by experts as ‘the mass detention of civilians without trial.’ And that’s exactly what this administration is doing."

Some had strongly negative reactions.